The use of LEDs in place of conventional incandescent, fluorescent, and neon light sources has a number of advantages. LEDs tend to be less expensive and longer lasting than conventional incandescent, fluorescent, and neon light sources. In addition, LEDs generally can output more light per watt of electricity than incandescent, fluorescent, and neon light sources. Further, LEDs typically generate less heat during operation than conventional incandescent, fluorescent, and compact fluorescent light sources.
While the minimization of heat generation with LEDs is beneficial for interior fixtures (because air conditioners do not have to also overcome the heat being generated by the LED fixtures in addition to ambient temperatures and other electrical devices), it can actually cause some problems for exterior fixtures. For example, during the winter, in certain locations, snow and ice (also known as frozen precipitation) builds up on lighting fixtures, including street lights and traffic signal lights. Those street lights and traffic signal lights using conventional incandescent or fluorescent fixtures generate enough heat to prevent snow and ice from building up on the lens of the fixture. However, since LED-based fixtures don't generate as much heat, there is a tendency for them to allow for more ice and snow build-up on the lens area of the fixture. This build-up reduces the amount of light being output by the fixture, thereby reducing its effectiveness. In the case of traffic signal lights, the build-up can be such that motorists are unable to determine what the signal is and thereby creates an unsafe situation.